A lithium-ion battery with wide temperature chemical stability and glass sealing structure

Abstract

The present invention provides a lithium-ion battery with wide temperature chemical stability and glass sealing structure, the lithium-ion battery includes a battery housing, a glass sealing structure and an electrolyte, the wide temperature chemically stable electrolyte includes an organic solvent and an additive, the organic solvent includes EC, PC, EMC and EP, the additive includes VC, FEC, LiDFOB and MB; the glass sealing structure includes a stainless steel housing, a molybdenum column and anti-corrosion aluminosilicate glass, the molybdenum column runs through the stainless steel housing, and the anti-corrosion aluminosilicate glass seals the gap between the molybdenum column and the stainless steel housing; the glass sealing structure is located at the opening of the battery housing, and the sealing is achieved by the mutual buckling of the stainless steel housing and the battery housing. The lithium-ion battery of the present invention can prevent battery leakage, meet the demand of releasing more electric energy in a small space, and ensure good electrical performance under extreme temperatures.

Description

Technical Field

[0001] The invention belongs to the field of lithium ion batteries and relates to a lithium ion battery with wide temperature chemical stability and a glass sealing structure. Background Art

[0002] Lithium-ion batteries are widely used in the field of electrochemical energy storage due to their high energy density, long service life, no memory effect, clean and efficient. However, if the electrolyte of lithium-ion batteries leaks or comes into contact with air, it will seriously affect the performance and battery life and cause safety problems. In addition, based on its chemical properties, the performance of lithium-ion batteries will drop significantly at low temperatures, and self-discharge and capacity will drop sharply at high temperatures. Therefore, lithium-ion batteries can only operate at temperatures close to room temperature. At the same time, polymer sealing structures are generally used for the sealing of lithium-ion batteries. However, after long-term storage or operation, the polymer is corroded or damaged, and hardened, resulting in insufficient elasticity, leading to electrolyte leakage problems. In an environment with higher temperatures, the above situation is more likely to occur due to the principle of cold contraction and hot expansion.

[0003] The prior art has proposed some improvement schemes. For example, in order to improve the high temperature performance of lithium ion batteries, solvents with higher boiling points such as diethyl carbonate and ethyl methyl carbonate are generally selected as the main solvent of the electrolyte. However, these solvents have higher melting points, and the conductivity of the electrolyte drops very quickly at low temperatures, and the battery impedance increases rapidly, which makes it difficult to meet the low temperature discharge performance of the battery. On the other hand, selecting carboxylic acid esters with lower melting points such as ethyl acetate and ethyl propionate as the main solvent of the electrolyte can be beneficial to the low temperature performance of the battery, but the boiling points of these solvents are relatively low, which weakens the high temperature stability of the electrolyte, which is not conducive to improving the high temperature performance of the battery. In terms of additives, in order to improve the high temperature performance, additives such as vinylene carbonate and vinyl ethylene carbonate are generally used, but this type of additive will cause the battery impedance to be larger, especially at low temperatures, the battery impedance increases significantly, resulting in a decrease in the low temperature performance of the battery. Therefore, it is a more difficult topic to improve the high temperature performance and low temperature performance of the battery by electrolyte at the same time.

[0004] CN106252639A discloses a high-capacity lithium-ion battery electrolyte that takes into account both high and low temperature performance. The electrolyte includes a non-aqueous solvent and lithium hexafluorophosphate, and the electrolyte also includes a negative electrode film-forming additive, a flatulence inhibitor, and a low impedance additive; wherein the negative electrode film-forming additive is composed of fluoroethylene carbonate accounting for 3 to 15% of the total mass of the electrolyte; the flatulence inhibitor is composed of one or two of 1,3-propylene sultone or anhydride compounds accounting for 0.3 to 5% of the total mass of the electrolyte; the low impedance additive is composed of one or two of lithium difluorophosphate or lithium difluorooxalate phosphate accounting for 0.2 to 3% of the total mass of the electrolyte. The electrolyte is suitable for lithium-ion batteries with high nickel positive electrodes and silicon-carbon composite negative electrodes, while taking into account the normal temperature cycle performance, the high temperature storage performance and low temperature discharge performance of the lithium-ion battery are improved. However, its high temperature stability and electrochemical performance at low temperature need to be further improved, and the lithium-ion battery prepared by the electrolyte is prone to leakage, and the organic solvent used is toxic and easy to cause pollution.

[0005] CN209150167U discloses a kind of anti-leakage lithium battery, including a central column, a capacitor film, a shell and a shell bottom, wherein the capacitor film is wound on the central column to form an electric core shaft, and the electric core shaft is located inside the shell, and the shell bottom includes a base and a flexible layer located above the base, and the boundary of the flexible layer is tilted upward to form a protective ring, and the size of the protective ring is not less than the size of the base, and the bottom of the electric core shaft is located in the protective ring, and the protective ring is located inside the shell. The anti-leakage lithium battery described in it is adopted, and by adding a flexible layer at the bottom of the shell, a protective layer can be formed when the battery is squeezed by an external force to cause the bottom to rupture or the bottom and the shell are separated to form cracks, and the internal electrolyte is prevented from leaking out, and at extreme temperatures, due to the aging of the flexible layer, it is difficult to ensure the good sealing of the lithium battery. However, when the battery described in it is discharged by high and low temperature pulses, the voltage drop is relatively high. The SEI stability formed by it is also relatively weak, resulting in the formation of ruptures, side reactions, and the precipitation of positive metal ions when the high and low temperature cycles.

[0006] The above scheme has the problems of poor high and low temperature cycle performance, difficulty in making the battery have a good sealing effect when used in a wide temperature range due to the sealing structure, and reduced volume energy density of the battery caused by the sealing structure. Therefore, it is very necessary to develop a lithium-ion battery with good high and low temperature performance, which can meet the needs of releasing more electrical energy in a small space and prevent battery leakage. Summary of the invention

[0007] The purpose of the present invention is to provide a lithium-ion battery with wide temperature chemical stability and glass sealing structure. The lithium-ion battery of the present invention can prevent battery leakage, meet the demand of releasing more electric energy in a small space, and ensure good electrical performance at extreme temperatures (such as -40°C or 85°C). To achieve this purpose of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a lithium ion battery with wide temperature chemical stability and a glass sealing structure, wherein the lithium ion battery comprises a battery housing, a glass sealing structure and an electrolyte with wide temperature chemical stability;

[0009] The wide temperature and chemically stable electrolyte comprises an organic solvent and an additive, wherein the organic solvent comprises ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC) and ethyl propionate (EP), and the additive comprises vinylene carbonate (VC), fluoroethylene carbonate (FEC), lithium difluorooxalatoborate (LiDFOB) and methyl butyrate (MB);

[0010] The glass sealing structure includes a stainless steel shell, a molybdenum column and corrosion-resistant aluminosilicate glass, wherein the molybdenum column runs through the stainless steel shell, and the corrosion-resistant aluminosilicate glass seals the gap between the molybdenum column and the stainless steel shell; the glass sealing structure is located at the opening of the battery shell, and sealing is achieved by the mutual buckling of the stainless steel shell and the battery shell.

[0011] The lithium-ion battery of the present invention uses a glass sealing structure to seal the battery opening. The glass sealing structure is more resistant to corrosion than a polymer and has a smaller thermal expansion ratio, so that the battery has a good sealing effect when used in a wide temperature range. At the same time, the glass sealing structure has a small volume share and can meet the demand for releasing more electrical energy in a small space. It can effectively solve the problem of electrolyte leakage, especially the problem of battery leakage at high temperature, and extend the battery life.

[0012] In the lithium ion battery of the present invention, the wide temperature chemically stable electrolyte can ensure good high temperature performance and low temperature performance through the coordination of various components, and exhibits good wide temperature chemical stability. In a wide temperature range involving extreme temperatures (e.g., -40 to 85°C), the pulse discharge is stable, and after the pulse discharge, the battery voltage retention value is high. At -40°C, the 7C pulse discharge is performed for 10 seconds, and the voltage is maintained above 2.2V (the starting voltage is 3.67V, and the current is 350mA). At 85°C, the 7C pulse discharge is performed for 10 seconds, and the voltage is maintained above 3.59V (the starting voltage is 3.67V, and the current is 350mA).

[0013] Ethylene carbonate (EC) has a high dielectric constant (90), which can improve the insulation of the electrolyte and reduce the self-discharge problem of the battery. EC is also a good film-forming agent and participates in the formation of a stable SEI. However, the melting point of EC (36°C) is too high. At temperatures below the melting point of EC, the viscosity of the electrolyte increases and the conductivity of lithium ions decreases, which significantly affects the low-temperature charge and discharge performance of the lithium battery. The present invention optimizes the carbonate solvent component and partially replaces EC with PC. Since PC has a higher dielectric constant like EC and a lower melting point, it effectively improves the low-temperature performance of the battery.

[0014] The inventors conducted a large number of experiments and found through comparison and screening that among the low-temperature additives with lower melting points and low viscosities that have been commercialized, the melting points of EP and MB are lower than -70°C. When applied to the electrolyte system of the present invention, they can effectively reduce the viscosity of the electrolyte at low temperatures, thereby improving the lithium ion conductivity at low temperatures. Further optimizing the content of EP and MB can further improve the low-temperature performance of the battery.

[0015] VC and FEC are effective negative electrode film-forming agents, which can form a stable passivation film on the surface of the negative electrode, thereby effectively reducing the occurrence of negative electrode side reactions. The present invention also adds LiDFOB, which can chelate with transition metal ions to form a passivation film on the surface of the positive electrode material, thereby preventing the dissolution of transition metal ions and stabilizing the positive electrode material. Secondly, LiDFOB can react with Li ions, participate in the formation of SEI film and form a passivation film on the surface of the negative electrode material, thereby protecting the negative electrode material (such as graphite negative electrode material) and increasing the high temperature stability of the lithium ion battery. In addition, LiDFOB has a relatively high solubility and can increase the ionic conductivity of the electrolyte, thereby improving the low temperature performance of the battery.

[0016] Preferably, based on 100% volume of the organic solvent, the volume fraction of the ethylene carbonate is 10-15%, for example, 10%, 11%, 12%, 13%, 14% or 15%.

[0017] Preferably, based on 100% volume of the organic solvent, the volume fraction of the propylene carbonate is 1-10%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.

[0018] Preferably, based on 100% volume of the organic solvent, the volume fraction of the ethyl methyl carbonate is 5-30%, for example, 5%, 10%, 15%, 20%, 25% or 30%.

[0019] Preferably, based on 100% volume of the organic solvent, the volume fraction of the ethyl propionate is 50-80%, for example, 50%, 60%, 65%, 70%, 75% or 80%.

[0020] Preferably, based on the mass of the organic solvent as 100%, the mass fraction of the vinylene carbonate is 0-2% and does not include 0%, for example: 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.5% or 2%, etc., the mass fraction of the fluoroethylene carbonate is 0-2% and does not include 0%, for example: 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.5% or 2%, etc., the mass fraction of the lithium difluorooxalatoborate is 0-10% and does not include 0%, for example: 0.1%, 1%, 2%, 3%, 5%, 8% or 10%, etc., the mass fraction of the methyl butyrate is 0-20% and does not include 0%, for example: 0.1%, 1%, 3%, 8%, 10%, 12%, 15% or 20%, etc.

[0021] Preferably, based on 100% of the mass of the organic solvent, the mass fraction of the vinylene carbonate is 0.5-2%, for example, 0.5%, 0.8%, 1%, 1.2%, 1.5% or 2%.

[0022] Preferably, based on 100% of the mass of the organic solvent, the mass fraction of the fluoroethylene carbonate is 0.5-2%, for example, 0.5%, 0.8%, 1%, 1.2%, 1.5% or 2%.

[0023] Preferably, based on the mass of the organic solvent being 100%, the mass fraction of the lithium difluorooxalatoborate is 0.1 to 7.5%, for example, 0.1%, 1%, 3%, 5% or 7.5%, etc., preferably 0.5 to 2.5%.

[0024] Preferably, based on the mass of the organic solvent being 100%, the mass fraction of the methyl butyrate is 2.5-20%, for example, 2.5%, 5%, 10%, 15% or 20%, etc., preferably 5-15%.

[0025] Preferably, the electrolyte also includes lithium hexafluorophosphate.

[0026] Preferably, the concentration of lithium hexafluorophosphate is 0.5-1.5 mol / L, for example, 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L or 1.5 mol / L.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The lithium-ion battery of the present invention uses an optimized wide-temperature chemically stable electrolyte, and has stable pulse discharge in a wide temperature range involving extreme temperatures (e.g., -40 to 85°C), and the battery voltage retention value is high after pulse discharge. At the same time, by adopting a glass sealing structure, the problem of electrolyte leakage, especially the problem of battery leakage at high temperature, is effectively solved, thereby extending the battery life.

[0029] (2) The lithium-ion battery of the present invention, by using an optimized wide-temperature chemically stable electrolyte, has stable pulse discharge within a wide temperature range involving extreme temperatures (e.g., -40 to 85°C), and the battery voltage retention value is high after pulse discharge. The battery using the wide-temperature chemically stable electrolyte is sealed with a glass sealing structure, so that the battery can show excellent overall performance: after the battery is stored in high and low temperature cycles (-40 to 72°C), the battery voltage, weight and internal resistance are stable, and the capacity retention rate is high; after high temperature (85°C) charge and discharge cycles, the capacity retention rate is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 1-battery housing, 2-insulating sheet, 3-battery core, 4-wide temperature chemically stable electrolyte, 5-insulating surface sheet, 6-molybdenum column, 7-corrosion-resistant glass, 8-stainless steel housing, 9-positive electrode ear, and 10-negative electrode ear.

[0031] Figure 2 1 is a graph showing the thermal expansion test results of the anti-corrosion glass in one embodiment of the present invention.

[0032] Figure 3 This is a pulse discharge test voltage comparison chart of button cells made from the electrolytes obtained in Preparation Examples 1-6 of the present invention at -40°C, with a discharge rate of 7C and a discharge time of 10s.

[0033] Figure 4 It is a comparison chart of high temperature cycle tests of the lithium ion batteries described in Example 1 of the present invention and Comparative Example 1.

[0034] Figure 5 It is a comparison chart of weight changes of the lithium ion batteries described in Example 1 of the present invention and Comparative Example 1 under high and low temperature cycles.

[0035] Figure 6 It is a comparison diagram of voltage changes of the lithium ion batteries described in Example 1 of the present invention and Comparative Example 1 under high and low temperature cycles.

[0036] Figure 7 It is a comparison diagram of the internal resistance changes of the lithium ion batteries described in Example 1 of the present invention and Comparative Example 1 under high and low temperature cycles.

[0037] Figure 8It is a comparison chart of the self-discharge of the lithium ion batteries described in Example 1 of the present invention and Comparative Example 1 at 85°C.

[0038] Fig. 9 It is a comparison chart of the capacity change of the lithium ion batteries of Example 1 of the present invention and Comparative Example 1 after being stored at 85° C. for 21 days, and the starting voltage is 3.67V.

[0039] Fig.10 It is a comparison chart of the capacity change of the lithium ion batteries of Example 1 of the present invention and Comparative Example 1 after being stored at 85° C. for 21 days, with a starting voltage of 4.1V.

[0040] Fig.11 It is a comparison chart of the internal resistance change of the lithium ion batteries described in Example 1 of the present invention and Comparative Example 1 after being stored at 85° C. for 21 days.

[0041] Fig.12 It is a comparison chart of pulse discharge test of the lithium ion battery described in Example 1 of the present invention and Comparative Example 1 at -40°C, with a discharge rate of 7C and a discharge time of 10s.

[0042] Fig.13 It is a comparison chart of pulse discharge tests of the lithium ion batteries described in Example 1 of the present invention and Comparative Example 1 at 85° C., with a discharge rate of 7C and a discharge time of 10s.

[0043] Fig.14 It is a comparison chart of the normal temperature cycle (2.5-4.1V) test of the lithium ion batteries described in Example 1 of the present invention and Comparative Example 4.

[0044] Fig.15 It is a comparison chart of the normal temperature cycle (2.5-3.67V) test of the lithium ion battery described in Example 1 of the present invention and Comparative Example 4. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0046] In the present invention, room temperature refers to 25°C.

[0047] In a specific embodiment, the present invention provides a lithium ion battery having a wide temperature chemical stability and a glass sealing structure (see the structural schematic diagram Figure 1 ), the lithium-ion battery comprises a battery housing 1, a glass sealing structure and an electrolyte 4 which is chemically stable over a wide temperature range;

[0048] Wherein, the wide temperature and chemically stable electrolyte 4 comprises an organic solvent and an additive, wherein the organic solvent comprises EC, PC, EMC and EP, and the additive comprises VC, FEC, LiDFOB and MB;

[0049] The glass sealing structure includes a stainless steel shell 8, a molybdenum column 6 and an anti-corrosion glass 7, wherein the molybdenum column 6 passes through the stainless steel shell 8, and the anti-corrosion glass 7 seals the gap between the molybdenum column 6 and the stainless steel shell 8; the glass sealing structure is located at the opening of the battery shell 1, and sealing is achieved by the mutual buckling of the stainless steel shell 8 and the battery shell 1.

[0050] Furthermore, the stainless steel shell 8 and the battery housing 1 are connected by welding.

[0051] Furthermore, an insulating sheet 2 is provided between the bottom of the battery housing 1 and the battery core 3 .

[0052] Furthermore, at the opening of the battery housing 1 , an insulating sheet 2 is provided on the side of the stainless steel shell 8 facing the battery cell 3 , and an insulating surface sheet 5 is provided on the side facing away from the battery cell 3 .

[0053] Furthermore, the lithium-ion battery further comprises a positive electrode tab 9 and a negative electrode tab 10 , wherein the positive electrode tab 9 is an aluminum strip, and the negative electrode tab 10 is a nickel strip.

[0054] Preparation Example 1

[0055] This preparation example provides an electrolyte, the electrolyte comprising an organic solvent, lithium hexafluorophosphate and an additive, the organic solvent consisting of EC, EMC, EP and PC in a volume ratio of 10:5:80:5, and the additive consisting of VC, FEC, LiDFOB and MB;

[0056] Taking the total mass of the organic solvent as 100%, the mass concentration of lithium hexafluorophosphate is 1 mol / L, the mass concentration of VC is 1%, the mass concentration of FEC is 1.5%, the mass concentration of LiDFOB is 2%, and the mass concentration of MB is 10%.

[0057] Preparation Example 2

[0058] The only difference between this preparation example and preparation example 1 is that the mass concentration of MB is 3%, and the other conditions and parameters are exactly the same as those in preparation example 1.

[0059] Preparation Example 3

[0060] The only difference between this preparation example and preparation example 1 is that the mass concentration of MB is 5%, and the other conditions and parameters are exactly the same as those in preparation example 1.

[0061] Preparation Example 4

[0062] The only difference between this preparation example and preparation example 1 is that the mass concentration of MB is 15%, and the other conditions and parameters are exactly the same as those in preparation example 1.

[0063] Preparation Example 5

[0064] The only difference between this preparation example and preparation example 1 is that the mass concentration of MB is 20%, and the other conditions and parameters are exactly the same as those in preparation example 1.

[0065] Preparation Example 6

[0066] The only difference between this preparation example and preparation example 1 is that the mass concentration of MB is 0%, and the other conditions and parameters are exactly the same as those in preparation example 1.

[0067] The electrolyte of Preparation Example 1-6 is used to prepare a button cell, and the preparation method is as follows:

[0068] 1) Place the stainless steel sheet in the negative battery case

[0069] 2) Place the positive electrode face up on the stainless steel sheet

[0070] 3) Add 40 μL electrolyte

[0071] 4) Cover the diaphragm on the positive electrode sheet (positive electrode active material is NCM811)

[0072] 5) Add another 40 μL of electrolyte

[0073] 6) Place the negative electrode face down on the diaphragm

[0074] 7) Place the stainless steel sheet on the negative electrode sheet (the negative electrode active material is graphite)

[0075] 8) Place the spring on the stainless steel sheet

[0076] 9) Finally, cover the positive battery case

[0077] The button cells were sealed using a button cell sealing machine at a pressure of 750 psi.

[0078] The button cell was subjected to an extreme temperature pulse discharge test, with a target temperature of -40°C and a discharge rate of 7C for 10s. The test results are as follows: Figure 3 As shown by Figure 3 It can be seen that after pulse discharge at -40°C, the voltage of the button cells of Preparation Examples 2, 5 and 6 drops rapidly, and there is an optimal range for the amount of MB added, with better effects in the range of 5-15%.

[0079] Example 1

[0080] This embodiment provides a lithium-ion battery with wide temperature chemical stability and glass sealing structure, based on a specific implementation method, such as Figure 1 As shown, the material of the battery housing 1 is stainless steel, the anti-corrosion glass 7 is anti-corrosion aluminosilicate glass, in which the mass fraction of silicon is 29.6%, the mass fraction of aluminum is 5.6%, the mass fraction of sodium is 4.7%, and the mass fraction of oxygen is 60.1%. The thermal expansion test results of the anti-corrosion aluminosilicate glass are shown in FIG. Figure 2 The electrolyte used is the electrolyte provided in Preparation Example 1.

[0081] The positive electrode active material used in the lithium-ion battery of this embodiment is NCM811, and the negative electrode active material is graphite.

[0082] Comparative Example 1

[0083] This comparative example provides a lithium-ion battery, wherein the lithium-ion battery uses a conventional electrolyte and a polymer sealing structure, wherein the conventional electrolyte comprises an organic solvent, lithium hexafluorophosphate and an additive, wherein the organic solvent comprises EC, EMC and EP in a volume ratio of 15:5:80;

[0084] The additive consists of VC and FEC;

[0085] Taking the total mass of the organic solvent as 100%, the mass concentration of lithium hexafluorophosphate is 1 mol / L, the mass concentration of VC is 1%, and the mass concentration of FEC is 1.5%.

[0086] The lithium ion batteries of Example 1 and Comparative Example 1 were subjected to high temperature cycle test, high and low temperature cycle test, high temperature self-discharge test, high temperature storage test and extreme temperature pulse discharge test. The results are shown in Figure 4-13 , the test method is as follows:

[0087] ①High temperature cycle test

[0088] Table 1

[0089]

[0090] ②High and low temperature cycle test

[0091] Table 2

[0092]

[0093] NOTE: The maximum time interval between the high and low temperature extremes in step 1 is 30 minutes

[0094] ③High temperature self-discharge and high temperature storage test

[0095] Table 3

[0096]

[0097] ④Extreme temperature pulse discharge test

[0098] Table 4

[0099]

[0100] Depend on Figure 4 It can be seen that after high-temperature cycling, the lithium-ion battery provided by the embodiment of the present invention has a high battery capacity percentage (battery capacity percentage = capacity after cycling / first discharge capacity), and after 500 cycles, the capacity retention rate is above 61%, which is mainly attributed to the glass sealing structure and the wide-temperature chemically stable electrolyte. Comparative Example 1 uses a conventional sealing structure and electrolyte, and the battery capacity decreases significantly after high-temperature cycling.

[0101] Depend on Figure 5-7 It can be seen that after the lithium-ion battery provided by the embodiment of the present invention has undergone high and low temperature cycles, the changes in weight, voltage and internal resistance are smaller, and the glass sealing structure and the wide-temperature chemically stable electrolyte improve the stability of the lithium-ion battery under temperature changes.

[0102] Depend on Figure 8 It can be seen that the lithium-ion battery provided by the embodiment of the present invention has a slower voltage drop rate, reflecting its slower self-discharge rate. The glass sealing structure and the wide-temperature chemically stable electrolyte improve the self-discharge performance of the lithium-ion battery at high temperatures.

[0103] Depend on Figure 9-11 It can be seen that the capacity and internal resistance of the lithium-ion battery provided by the embodiment of the present invention stored at 85° C. for 21 days change less, and the glass sealing structure and the wide-temperature chemically stable electrolyte improve the stability of the lithium-ion battery at high temperatures.

[0104] Depend on Fig.12 It can be seen that the glass-sealed lithium-ion battery of the present invention uses an optimized electrolyte and glass-sealed structure, so that the voltage of the battery remains above 2 V after low-temperature high-current discharge. In contrast, the voltage of the lithium-ion battery of Comparative Example 1 drops below 1.5 V after low-temperature discharge.

[0105] Depend on Fig.13 It can be seen that the lithium ion battery with a glass-sealed lithium ion structure described in the present invention uses an optimized electrolyte and a glass sealing structure, so that the voltage of the battery is always maintained above 3.58V after high-temperature and high-current discharge. On the contrary, the voltage of the lithium ion battery of Comparative Example 1 drops below 3.52V after high-temperature discharge.

[0106] Comparative Example 2

[0107] The only difference between this comparative example and Example 1 is that the electrolyte is the electrolyte provided in Preparation Example 6, to which MB is not added.

[0108] The lithium ion battery of Comparative Example 2 was subjected to an extreme temperature pulse discharge test using the same test method as Example 1, with a target temperature of -40°C. After the -40°C pulse discharge, the voltage of the lithium ion battery of Comparative Example 2 dropped rapidly. Compared with Example 1, it can be seen that not adding MB is not conducive to improving the low temperature performance.

[0109] Comparative Example 3

[0110] The only difference between this comparative example and Example 1 is that LiDFOB is not added to the electrolyte, and the other conditions and parameters are exactly the same as those in Example 1.

[0111] The lithium ion battery of Comparative Example 3 was subjected to a high temperature cycle test using the same test method as in Example 1. After 500 cycles, the capacity retention rate was less than 50%. Compared with Example 1, it can be seen that not adding LiDFOB is not conducive to improving the high temperature cycle performance.

[0112] Comparative Example 4

[0113] The only difference between this comparative example and Example 1 is that the glass sealing structure is replaced with a polymer sealing structure, and the other conditions and parameters are exactly the same as those in Example 1.

[0114] The lithium-ion batteries of Example 1 and Comparative Example 4 (three groups each) were subjected to room temperature charge and discharge cycle tests. The results are shown in Figure 14-15 , the test method is as follows:

[0115] Table 5

[0116]

[0117] Table 6

[0118]

[0119]

[0120] Depend on Figure 14-15 It can be seen that the lithium-ion battery provided by the embodiment of the present invention has a high capacity retention rate after 3000 charge and discharge cycles at room temperature, and the glass sealing structure can improve the cycle stability of the lithium-ion battery at room temperature.

[0121] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A lithium-ion battery with a wide temperature range of -40 to 85°C and chemical stability and a glass sealing structure, the lithium-ion battery comprising a battery housing, characterized in that: The lithium-ion battery comprises a glass sealing structure and an electrolyte that is chemically stable over a wide temperature range; The wide temperature and chemically stable electrolyte comprises an organic solvent and an additive, wherein the organic solvent is composed of ethylene carbonate, propylene carbonate, ethyl methyl carbonate and ethyl propionate, and the additive is composed of vinylene carbonate, fluoroethylene carbonate, lithium difluorooxalatoborate and methyl butyrate; The glass sealing structure comprises a stainless steel shell, a molybdenum column and anti-corrosion aluminosilicate glass, wherein the molybdenum column penetrates the stainless steel shell, and the anti-corrosion aluminosilicate glass seals the gap between the molybdenum column and the stainless steel shell; the glass sealing structure is located at the opening of the battery shell, and the sealing is achieved by the mutual buckling of the stainless steel shell and the battery shell; Based on the volume of the organic solvent being 100%, the volume fraction of the ethylene carbonate is 10-12%, the volume fraction of the propylene carbonate is 1-8%, and the volume fraction of the ethyl propionate is 50-80%; Taking the mass of the organic solvent as 100%, the mass fraction of the methyl butyrate is 5-15%.

2. The lithium-ion battery according to claim 1, characterized in that Based on the volume of the organic solvent being 100%, the volume fraction of the ethyl methyl carbonate is 5-30%.

3. The lithium ion battery according to claim 1, characterized in that Taking the mass of the organic solvent as 100%, the mass fraction of the vinylene carbonate is 0-2% and does not include 0%, the mass fraction of the fluoroethylene carbonate is 0-2% and does not include 0%, and the mass fraction of the lithium difluorooxalatoborate is 0-10% and does not include 0%.

4. The lithium ion battery according to claim 1, characterized in that Taking the mass of the organic solvent as 100%, the mass fraction of the vinylene carbonate is 0.5-2%.

5. The lithium ion battery according to claim 1, characterized in that Taking the mass of the organic solvent as 100%, the mass fraction of the fluoroethylene carbonate is 0.5-2%.

6. The lithium ion battery according to claim 3, characterized in that Taking the mass of the organic solvent as 100%, the mass fraction of the lithium difluorooxalatoborate is 0.1-7.5%.

7. The lithium ion battery according to claim 6, characterized in that Taking the mass of the organic solvent as 100%, the mass fraction of the lithium difluorooxalatoborate is 0.5-2.5%.

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